Geiselhardt Sven, Hilker Monika, Müller Frank, Kozlov Mikhail V, Zvereva Elena L
Institute of Biology, Dahlem Centre of Plant Sciences, Freie Universität Berlin, Haderslebener Str. 9, D-12163, Berlin, Germany.
J Chem Ecol. 2015 Mar;41(3):276-86. doi: 10.1007/s10886-015-0558-x. Epub 2015 Mar 25.
We explored the inter- and intrapopulation variability in the larval defensive chemistry of the leaf beetle Chrysomela lapponica with respect to the salicylic glycoside (SG) content of its host species. Secretions of larvae from three populations associated in nature with SG-poor willows contained nearly twice as many components and 40-fold higher concentrations of autogenously produced isobutyrates and 2-methylbutyrates than secretions of larvae from three populations associated with SG-rich willows, which in turn had 200-fold higher concentrations of host-derived salicylaldehyde. Reciprocal transfer experiments showed that the larvae from populations associated with SG-rich willows did not produce appreciable amounts of butyrates on either SG-rich or SG-poor willows, while populations feeding on several SG-poor willow species retained the ability for efficient sequestration of SGs, along with their ability to produce high amounts of isobutyrates and 2-methylbutyrates. Only the populations associated with SG-poor willows demonstrated among-family variation in the composition of defensive secretion and differential responses of individual families to willows with alternative SG levels, which can be seen as the prerequisites for shifting to novel hosts. These non-specialized populations show a dual defensive strategy, which corresponds to the ancestral state of this species, while populations that fully depend on host-derived toxins (feeding on SG-rich willows) or have lost the ability to produce salicylaldehyde (feeding on birches) are most deviant from the ancestral state. The results indicate that defensive strategies may differ between populations within a species, and suggest that this variation reduces extinction risks and maintains the high ecological diversity and wide distribution of C. lapponica.
我们研究了叶甲Chrysomela lapponica幼虫防御化学的种群间和种群内变异性，该变异性与宿主植物的水杨苷（SG）含量有关。在自然环境中，与SG含量低的柳树相关的三个种群的幼虫分泌物所含成分数量几乎是与SG含量高的柳树相关的三个种群的幼虫分泌物的两倍，并且其自身产生的异丁酸酯和2-甲基丁酸酯的浓度高出40倍，而与SG含量高的柳树相关的幼虫分泌物中宿主衍生的水杨醛浓度则高出200倍。相互转移实验表明，与SG含量高的柳树相关的种群的幼虫在SG含量高或低的柳树上均不会产生大量丁酸酯，而以几种SG含量低的柳树为食的种群则保留了有效隔离SG的能力，以及产生大量异丁酸酯和2-甲基丁酸酯的能力。只有与SG含量低的柳树相关的种群在防御分泌物组成上表现出家族间差异，以及各个家族对SG水平不同的柳树的不同反应，这可被视为转向新宿主的先决条件。这些非特化种群表现出一种双重防御策略，这与该物种的祖先状态相对应，而完全依赖宿主衍生毒素（以SG含量高的柳树为食）或已丧失产生水杨醛能力（以桦树为食）的种群则与祖先状态差异最大。结果表明，一个物种内不同种群的防御策略可能不同，并表明这种变异降低了灭绝风险，维持了拉普兰叶甲的高生态多样性和广泛分布。
